Biology subjects

Donald, P. F.

Publications and source records attributed to Donald, P. F..

7 recordsLinked to original sources

bioRxiv2025

Predicting the responses of the world's bird species to increases in agricultural production

The intensification and expansion of croplands are among the greatest threats to biodiversity, but the likely responses to these changes remain unknown for most species. Using data on responses of 862 bird species to changes in yields of arable crops, we extrapolate vulnerability to agriculture for the worlds other terrestrial birds based on their traits and taxonomy. We estimate that 74-78% of terrestrial bird species globally suffer population declines where natural habitats are replaced by croplands, and that over half cannot persist in cropland at even the lowest current yields. Past impacts of agriculture on birds have been greatest in the tropics, particularly in coastal forest regions of Central and South America and West Africa and in southern and South-East Asia. Using these estimates to model the impacts of future scenarios of agricultural change, we find that continuing current rates of cropland expansion and yield increases (i.e., extrapolating business-as-usual trends to 2050) is expected to have more negative impacts on birds (particularly in Central and South America, Eastern Europe, sub-Saharan Africa and South and East Asia) than a potential alternative of a targeted strategy of closing yield gaps while limiting cropland expansion. However, we also identify biodiverse regions of the world where closing yield gaps may have more severe impacts on birds than business-as-usual, such as the Pampas of South America and parts of the Sahel region in West Africa. The strategy of least impact for a particular area can be predicted from the response characteristics of the communities of species present there, offering opportunities to take account of regional context for designing less damaging global food production systems.

ecology↗

bioRxiv2023

Assessing the global prevalence of wild birds in trade

Trade represents a significant threat to many wild species and is often clandestine and poorly monitored. Information on which species are most prevalent in trade, and potentially threatened by it, therefore remains fragmentary. We mobilised seven global datasets on birds in trade to identify the species or groups of species that might be at particular risk. These datasets sample different parts of the broad trade spectrum but we nevertheless find a statistically strong congruence between them in which species are recorded in trade. Furthermore, the frequency with which species are recorded within datasets is positively correlated with their occurrence across datasets. This allows us to propose a trade prevalence score that can be applied to all bird species globally. This score discriminates well between species known from semi-independent assessments to be heavily or unsustainably traded and all other species. Globally, 45.1% of all bird species, and 36.7% of globally threatened bird species, were recorded in at least one of the seven datasets. Species listed in Appendices I or II of CITES, species with large geographical distributions and non-songbirds had higher trade prevalence scores. Speciose orders with high mean trade prevalence scores include the Falconiformes, Psittaciformes, Accipitriformes, Anseriformes, Bucerotiformes and Strigiformes. Despite their low mean prevalence score, Passeriformes accounted for the highest overall number of traded species of any order but had low representation in CITES Appendices. Geographical hotspots where large numbers of traded species co-occur differed between songbirds (South-East Asia and Eurasia) and non-songbirds (central South America, sub-Saharan Africa and India). This first attempt to quantify and map the relative prevalence in trade of all bird species globally can be used to identify species and groups of species which may be at particular risk of harm from trade and can inform conservation and policy interventions to reduce its adverse impacts. Article impact statementThe first metric to estimate the prevalence in trade of all the worlds bird species is presented.

ecology↗

bioRxiv2022

Area of Habitat maps for the world's terrestrial birds and mammals

Area of Habitat (AOH) is the habitat available to a species, that is, habitat within its range. It complements a geographic range map for a species by showing potential occupancy and reducing commission errors. AOH maps are produced by subtracting areas considered unsuitable for the species from their range map, using information on each species associations with habitat and elevation. We present AOH maps for 5,481 terrestrial mammal and 10,651 terrestrial bird species (including 1,816 migratory bird species for which we present separate maps for the resident, breeding and non-breeding areas). Our maps have a resolution of 100 m. On average, AOH covered 66{+/-}28% of the range maps for mammals and 64{+/-}27% for birds. The AOH maps were validated independently, following a novel two-step methodology: a modelling approach to identify outliers and a species-level approach based on point localities. We used AOH maps to produce global maps of the species richness of mammals, birds, globally threatened mammals and globally threatened birds.

ecology↗

bioRxiv2021

A validation standard for Area of Habitat maps for terrestrial birds and mammals

Area of Habitat (AOH) is a deductive model which maps the distribution of suitable habitat at suitable altitudes for a species inside its broad geographical range. AOH maps have been validated using presence-only data for small subsets of species for different taxonomic groups, but no standard validation method exists when absence data are not available. We develop a novel two-step validation protocol for AOH which includes first a model-based evaluation of model prevalence (i.e, the proportion of suitable habitat within a species range), and second a validation using species point localities (presence-only) data. We applied the protocol to AOH maps of terrestrial birds and mammals. In the first step we built logistic regression models to predict expected model prevalence (the proportion of the range retained as AOH) as a function of each species elevation range, mid-point of elevation range, number of habitats, realm and, for birds, seasonality. AOH maps with large difference between observed and predicted model prevalence were identified as outliers and used to identify a number of sources of systematic error which were then corrected when possible. For the corrected AOH, only 1.7% of AOH maps for birds and 2.3% of AOH maps for mammals were flagged as outliers in terms of the difference between their observed and predicted model prevalence. In the second step we calculated point prevalence, the proportion of point localities of a species falling in pixels coded as suitable in the AOH map. We used 48,336,141 point localities for 4889 bird species and 107,061 point localities for 420 mammals. Where point prevalence exceeded model prevalence, the AOH was a better reflection of species distribution than random. We also found that 4689 out of 4889 (95.9%) AOH maps for birds, and 399 out of 420 (95.0%) AOH maps for mammals were better than random. Possible reasons for the poor performance of a small proportion of AOH maps are discussed.

zoology↗

bioRxiv2021

A habitat class to land cover translation model for mapping Area of Habitat of terrestrial vertebrates

Area of Habitat (AOH) is defined as the habitat available to a species, that is, habitat within its range and is produced by subtracting areas of unsuitable land cover and elevation from the range. Habitat associations are documented using the IUCN Habitats Classification Scheme, and unvalidated expert opinion has been used so far to match habitat to land-cover classes generating a source of uncertainty in AOH maps. We develop a data-driven method to translate IUCN habitat classes to land-cover based on point locality data for 6,986 species of terrestrial mammals, birds, amphibians and reptiles. We extracted the land-cover class at each point locality and matched it to the IUCN habitat class(es) assigned to each species occurring there. Then we modelled each land cover class as a function of IUCN habitat using logistic regression models. The resulting odds ratios were used to assess the strength of the association of each habitat land-cover class. We then compared the performance of our data-driven model with those from a published expert knowledge translation table. The results show that some habitats (e.g. forest and desert) could be more confidently assigned to land-cover classes than others (e.g. wetlands and artificial). We calculated the association between habitat classes and land-cover classes as a continuous variable, but to map AOH, which is in the form of a binary presence/absence, it is necessary to apply a threshold of association. This can be chosen by the user according to the required balance between omission and commission errors. We demonstrate that a data-driven translation model and expert knowledge perform equally well, but the model provides greater standardization, objectivity and repeatability. Furthermore, this approach allows greater flexibility in the use of the results and allows uncertainty to be quantified. Our model can be developed regionally or for different taxonomic groups.

ecology↗

bioRxiv2020

Migration strategy and site fidelity of the globally threatened Sociable Lapwing Vanellus gregarius

Population declines of the critically endangered Sociable Lapwing are probably due to high mortality along its migration routes or on its wintering grounds, both of which are very poorly known. We therefore undertook a long-term study of the species movements using satellite tagging, colour-ringing and targeted field surveys. We also compiled a database of historical and recent sightings of the species from published and unpublished sources. There were two migration flyways from the breeding grounds in Kazakhstan, along which birds used different staging strategies. A longer western route (c. 5200 km) takes birds west to southern Russia, then south through the Caucasus and the Levant to wintering areas in Saudi Arabia and eastern Sudan. A shorter eastern route (c. 2800 km) takes birds south to Turkmenistan and Uzbekistan, then over the mountains of northern Afghanistan to wintering areas in Pakistan and north-western India. In spring, birds of the western flyway cut out the Caucasus by making a direct crossing of the Caspian Sea from Azerbaijan. The migration strategy is characterised by infrequent long-distance movements followed by often lengthy stopovers in a small number of staging areas that are used consistently across years, and by high individual and low between-individual consistency in patterns of movement, both spatially and temporally. At least four main autumn stopover areas and one additional spring stopover area were identified along the longer western route, but only one autumn and one spring staging area along the eastern route. There was no relationship between latitude or longitude of capture for tagging or colour ringing and the subsequent migration route used, and the same breeding colonies could contain breeding adults and produce chicks of both flyway populations, suggesting that no clear migratory divide exists within the breeding range. Sociable Lapwings spend around a third of the year on their breeding grounds, a third on their wintering grounds and a third moving between them. Birds were highly faithful to their passage and wintering sites, but showed low fidelity to breeding sites. The migration stopover areas and the wintering sites are usually located at the interface of agriculture, particularly irrigated cropland along rivers, and dry steppe-like or desert habitats. This species selects, and perhaps relies upon, agricultural habitats throughout its entire life cycle, and its heavy reliance on some of the worlds most anciently cultivated regions suggests that this synanthropic relationship may have evolved over many millennia. The recent emergence of irrigated cropfields in Arabia is likely to have allowed birds using the western route to winter well north of their previous wintering range and maybe to spread into new wintering areas along the coasts of the Arabian Gulf. The concentration of large numbers of birds at a small number of traditional but unprotected migration stopover areas offers the opportunity to quantify and monitor the global population size, for which we derive a tentative estimate of c. 24,000 individuals (95% CL: 13,700 - 55,560). However, it also makes the species particularly vulnerable to hunting and small-scale habitat change. Illegal hunting along the western flyway is identified as the most plausible driver of the species decline.

ecology↗

bioRxiv2020

The environmental impacts of palm oil and its alternatives

The destruction of ecosystems for vegetable oil production represents a major cause of global biodiversity loss and greenhouse gas emissions 1. Over the last two decades, oil palm, in particular, has caused societal concern due to its high impacts on biodiverse and carbon-dense tropical rainforests 2-8, leading to calls to source vegetable oils from alternative oil-producing crops. However, given the high yields of oil palm, how does that damage compare with other oil crops that require more land? Here, we estimate the carbon and biodiversity footprints, per unit of oil produced, of the worlds five major vegetable oil crops. We find that oil palm has the lowest carbon loss and species richness loss per-tonne-oil, but has a larger impact on range-restricted species than sunflower and rapeseed. We go on to identify global areas for oil crop expansion that will minimise future carbon and biodiversity impacts, and argue that closing current yield gaps and optimising the location of future growing areas will be much more effective at reducing future environmental impacts of global vegetable oil production than substituting any one crop for another.

ecology↗